Why SBD fuel endurance depends on the flight profile

How much additional flying time would twenty gallons of fuel give an SBD Dauntless?

There is no single figure without the flight profile; steady cruise lasts longer, while maneuvering consumes the remaining fuel much faster.

No precise flight-time figure for twenty gallons is offered from memory. The answer depends on whether the SBD is cruising steadily or maneuvering during a search or approach. Maneuvering raises fuel consumption and shortens the endurance available from the same quantity. A carrier commander therefore needs the mission profile as well as the gauge reading when deciding whether an aircraft can continue or must turn back.